U.S. Pat. No. 6,924,792, by the inventor hereof, teaches various approaches to using electric fields and/or electrowetting, and/or electrostatic techniques to move, or distort the shape of, liquid droplets located between polymer (or other) substrates were discussed, so as to change the color of light passing through display systems.
The droplet would typically—but not invariably—be located between two substrates or surfaces, at least one of which would present a hydrophobic surface to (and in respect of) the droplet(s), and said droplets could in some approaches be present together with one or more other liquids (typically one other) where said measures of liquid would, typically, be mutually-immiscible (e.g., a polar liquid droplet together with a non-polar liquid such as silicon oil).
Various different positions and designs of electrodes were discussed to induce the droplet due to electrowetting effect to change its location, or change its cross-sectional profile or contact area with an surface which may be hydrophobic in respect of that liquid in the absence, at least, of any electric field affecting the surface energy relationship between liquid and solid—and thereby to affect the passage of light passing onto or through the droplet, so that, for example, the droplet focussed light onto one or more selected colors on an adjacent multi-colored filter array—and thereafter passed on, towards the display screen.
The primary approaches discussed were (a) to change the location, or change the shape of, droplets of a suitable liquid functioning as optical lenses, which focussed light onto differently-colored color filters; and (b) using similar techniques, to change the location of dyed liquid droplets, passing one or more droplets of the desired color into light paths, so that they functioned as light filters. Optionally, suitable optical lens arrangements could cause the resulting colored light to ‘fill’ the pixel area of the display.
In this new patent application, we will discuss different dynamic color display screen and other light-modulating techniques, devices and approaches, which though in some cases employing many fundamentally similar means of changing the location or shape of droplets as were previously discussed, are also in these new approaches concerned with using the droplets to perform functions not previously discussed, or alternatively using the droplets in different display or light color-changing arrangements than were previously disclosed.
In any of the following approaches, it should be assumed that the means of inducing a change of location or shape of the droplet(s) is by employing electrowetting effect. There may be an electrically insulating layer between the droplet(s) which are affected by electrowetting effect and one or more electrodes located on the other side of a substrate with which the droplet is in contact; in other approaches, this electrically insulating layer may, optionally, be absent.
It should also be understood, with any of the approaches described below, that, optionally, any droplet or measure of liquid which due to a change of shape or location of that droplet due to electrowetting effect is causing a modulation of properties of light may be either directly affected by an electrowetting effect acting on it, or may alternatively be a measure of liquid which is caused to itself change its location or shape due to one or more other measures of liquid (which are affected by an electrowetting effect) coming into physical contact with such a measure of liquid (as a result of the other type of droplet's change of shape or location due by electrowetting effect)—and as a result, the latter droplet (unaffected by said electrowetting effect) is itself caused to change its own shape or location. In such circumstances, the above two different classes of droplets (or measures of liquid) would normally be mutually-immiscible. This may be termed ‘passive’ change of a droplet's location or shape, due to a change of shape or location due to electrowetting effect of some other measure of liquid, where the ‘active’ droplet as a result of its change of shape or location causes the ‘passive’ measure of liquid to itself change location or shape. This patent, and all the descriptions of different devices and arrangements for electrowetting devices, includes within its scope optical changes which occur as a result of either such a ‘passive’ or such an ‘active’ change or shape or location of any measure of liquid.